This invention relates to a fuel delivery system for a hand-held lighter of the type which employs liquid fuel, and more particularly to an inexpensive and reliable fuel delivery system for a lighter which stores its fuel as a liquid but utilizes it as a gas.
Recently, disposable hand-held lighters which utilize butane or mixtures of low molecular weight hydrocarbons as fuel have come into extensive use. These lighters have a reservoir which maintains the fuel in a liquid state under pressure and a manually operable valve, which when open, allows a flow of gaseous hydrocarbon fuel to the combustion compartment of the lighter. A conventional serrated wheel and flint provide a spark to ignite the fuel as it mixes with air in the combustion compartment.
Because the fuel is used in only very small increments, and because the lighters can be manufactured quite inexpensively, the user gets literally thousands of lights without replenishing the fuel, and it becomes economical to discard the lighter when the fuel is exhausted.
With most of these lighters, liquid fuel is vaporized at a flow-controlling pressure drop associated with the manually operable valve. The function of the orifice of the burner in these lighters is to direct the flow of gas at atmospheric pressure to the combustion compartment. Recently, improvements have been made which provide a wind-proof burner which requires a uniform flow of gaseous fuel under pressure for proper operation. In this case, the orifice itself produces the controlling pressure drop and drives a jet pump for aspiration of air for combustion. (see, for example, U.S. Pat. Nos. 3,844,707 and 3,915,623) Accordingly, there is a need for a simple and inexpensive fuel delivery system which will ensure that any fuel entering the orifice of such a burner be gaseous. Such a fuel delivery system must be simple and extremely small, made of inexpensive materials, and capable of being mass produced and easily installed in the lighters.
To accomplish these goals, the present invention utilizes a well known principle which has been employed in portable hand torches for providing a steady flow of gas from a liquid fuel reservoir. Specifically, it is known to provide a pressure reducing valve in the discharge passage leading from the fuel reservoir to the torch burner which seats against the gas pressure in the reservoir and is resiliently forced toward the seated position. This arrangement isolates the liquid fuel in the reservoir from the burner until the pressure beyond the valve combined with the valve's biasing force is insufficient to hold it in its seated position. Any liquid in the conduits therefore quickly volatilizes in the reduced pressure environment, and an even, uniform flow of gas to the burner is provided. However, the application of this principle to lighters of the type described is fraught with problems, i.e., the system must be simple, very small, and capable of manufacture and installation at a very low cost.